ginentrypage.c

postgresql8.3.4源码,开源数据库

		itupsz = MAXALIGN(IndexTupleSize(itup)) + sizeof(ItemIdData);
	}

	if (PageGetFreeSpace(page) + itupsz >= MAXALIGN(IndexTupleSize(btree->entry)) + sizeof(ItemIdData))
		return true;

	return false;
}

/*
 * Delete tuple on leaf page if tuples was existed and we
 * should update it, update old child blkno to new right page
 * if child split is occured
 */
static BlockNumber
entryPreparePage(GinBtree btree, Page page, OffsetNumber off)
{
	BlockNumber ret = InvalidBlockNumber;

	Assert(btree->entry);
	Assert(!GinPageIsData(page));

	if (btree->isDelete)
	{
		Assert(GinPageIsLeaf(page));
		PageIndexTupleDelete(page, off);
	}

	if (!GinPageIsLeaf(page) && btree->rightblkno != InvalidBlockNumber)
	{
		IndexTuple	itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, off));

		ItemPointerSet(&itup->t_tid, btree->rightblkno, InvalidOffsetNumber);
		ret = btree->rightblkno;
	}

	btree->rightblkno = InvalidBlockNumber;

	return ret;
}

/*
 * Place tuple on page and fills WAL record
 */
static void
entryPlaceToPage(GinBtree btree, Buffer buf, OffsetNumber off, XLogRecData **prdata)
{
	Page		page = BufferGetPage(buf);
	static XLogRecData rdata[3];
	OffsetNumber placed;
	static ginxlogInsert data;
	int			cnt = 0;

	*prdata = rdata;
	data.updateBlkno = entryPreparePage(btree, page, off);

	placed = PageAddItem(page, (Item) btree->entry, IndexTupleSize(btree->entry), off, false, false);
	if (placed != off)
		elog(ERROR, "failed to add item to index page in \"%s\"",
			 RelationGetRelationName(btree->index));

	data.node = btree->index->rd_node;
	data.blkno = BufferGetBlockNumber(buf);
	data.offset = off;
	data.nitem = 1;
	data.isDelete = btree->isDelete;
	data.isData = false;
	data.isLeaf = GinPageIsLeaf(page) ? TRUE : FALSE;

	/*
	 * Prevent full page write if child's split occurs. That is needed to
	 * remove incomplete splits while replaying WAL
	 *
	 * data.updateBlkno contains new block number (of newly created right
	 * page) for recently splited page.
	 */
	if (data.updateBlkno == InvalidBlockNumber)
	{
		rdata[0].buffer = buf;
		rdata[0].buffer_std = TRUE;
		rdata[0].data = NULL;
		rdata[0].len = 0;
		rdata[0].next = &rdata[1];
		cnt++;
	}

	rdata[cnt].buffer = InvalidBuffer;
	rdata[cnt].data = (char *) &data;
	rdata[cnt].len = sizeof(ginxlogInsert);
	rdata[cnt].next = &rdata[cnt + 1];
	cnt++;

	rdata[cnt].buffer = InvalidBuffer;
	rdata[cnt].data = (char *) btree->entry;
	rdata[cnt].len = IndexTupleSize(btree->entry);
	rdata[cnt].next = NULL;

	btree->entry = NULL;
}

/*
 * Returns new tuple with copied value from source tuple.
 * New tuple will not store posting list
 */
static IndexTuple
copyIndexTuple(IndexTuple itup, Page page)
{
	IndexTuple	nitup;

	if (GinPageIsLeaf(page) && !GinIsPostingTree(itup))
	{
		nitup = (IndexTuple) palloc(MAXALIGN(GinGetOrigSizePosting(itup)));
		memcpy(nitup, itup, GinGetOrigSizePosting(itup));
		nitup->t_info &= ~INDEX_SIZE_MASK;
		nitup->t_info |= GinGetOrigSizePosting(itup);
	}
	else
	{
		nitup = (IndexTuple) palloc(MAXALIGN(IndexTupleSize(itup)));
		memcpy(nitup, itup, IndexTupleSize(itup));
	}

	return nitup;
}

/*
 * Place tuple and split page, original buffer(lbuf) leaves untouched,
 * returns shadow page of lbuf filled new data.
 * Tuples are distributed between pages by equal size on its, not
 * an equal number!
 */
static Page
entrySplitPage(GinBtree btree, Buffer lbuf, Buffer rbuf, OffsetNumber off, XLogRecData **prdata)
{
	static XLogRecData rdata[2];
	OffsetNumber i,
				maxoff,
				separator = InvalidOffsetNumber;
	Size		totalsize = 0;
	Size		lsize = 0,
				size;
	static char tupstore[2 * BLCKSZ];
	char	   *ptr;
	IndexTuple	itup,
				leftrightmost = NULL;
	static ginxlogSplit data;
	Page		page;
	Page		lpage = GinPageGetCopyPage(BufferGetPage(lbuf));
	Page		rpage = BufferGetPage(rbuf);
	Size		pageSize = PageGetPageSize(lpage);

	*prdata = rdata;
	data.leftChildBlkno = (GinPageIsLeaf(lpage)) ?
		InvalidOffsetNumber : GinItemPointerGetBlockNumber(&(btree->entry->t_tid));
	data.updateBlkno = entryPreparePage(btree, lpage, off);

	maxoff = PageGetMaxOffsetNumber(lpage);
	ptr = tupstore;

	for (i = FirstOffsetNumber; i <= maxoff; i++)
	{
		if (i == off)
		{
			size = MAXALIGN(IndexTupleSize(btree->entry));
			memcpy(ptr, btree->entry, size);
			ptr += size;
			totalsize += size + sizeof(ItemIdData);
		}

		itup = (IndexTuple) PageGetItem(lpage, PageGetItemId(lpage, i));
		size = MAXALIGN(IndexTupleSize(itup));
		memcpy(ptr, itup, size);
		ptr += size;
		totalsize += size + sizeof(ItemIdData);
	}

	if (off == maxoff + 1)
	{
		size = MAXALIGN(IndexTupleSize(btree->entry));
		memcpy(ptr, btree->entry, size);
		ptr += size;
		totalsize += size + sizeof(ItemIdData);
	}

	GinInitPage(rpage, GinPageGetOpaque(lpage)->flags, pageSize);
	GinInitPage(lpage, GinPageGetOpaque(rpage)->flags, pageSize);

	ptr = tupstore;
	maxoff++;
	lsize = 0;

	page = lpage;
	for (i = FirstOffsetNumber; i <= maxoff; i++)
	{
		itup = (IndexTuple) ptr;

		if (lsize > totalsize / 2)
		{
			if (separator == InvalidOffsetNumber)
				separator = i - 1;
			page = rpage;
		}
		else
		{
			leftrightmost = itup;
			lsize += MAXALIGN(IndexTupleSize(itup)) + sizeof(ItemIdData);
		}

		if (PageAddItem(page, (Item) itup, IndexTupleSize(itup), InvalidOffsetNumber, false, false) == InvalidOffsetNumber)
			elog(ERROR, "failed to add item to index page in \"%s\"",
				 RelationGetRelationName(btree->index));
		ptr += MAXALIGN(IndexTupleSize(itup));
	}

	btree->entry = copyIndexTuple(leftrightmost, lpage);
	ItemPointerSet(&(btree->entry)->t_tid, BufferGetBlockNumber(lbuf), InvalidOffsetNumber);

	btree->rightblkno = BufferGetBlockNumber(rbuf);

	data.node = btree->index->rd_node;
	data.rootBlkno = InvalidBlockNumber;
	data.lblkno = BufferGetBlockNumber(lbuf);
	data.rblkno = BufferGetBlockNumber(rbuf);
	data.separator = separator;
	data.nitem = maxoff;
	data.isData = FALSE;
	data.isLeaf = GinPageIsLeaf(lpage) ? TRUE : FALSE;
	data.isRootSplit = FALSE;

	rdata[0].buffer = InvalidBuffer;
	rdata[0].data = (char *) &data;
	rdata[0].len = sizeof(ginxlogSplit);
	rdata[0].next = &rdata[1];

	rdata[1].buffer = InvalidBuffer;
	rdata[1].data = tupstore;
	rdata[1].len = MAXALIGN(totalsize);
	rdata[1].next = NULL;

	return lpage;
}

/*
 * return newly allocate rightmost tuple
 */
IndexTuple
ginPageGetLinkItup(Buffer buf)
{
	IndexTuple	itup,
				nitup;
	Page		page = BufferGetPage(buf);

	itup = getRightMostTuple(page);
	nitup = copyIndexTuple(itup, page);
	ItemPointerSet(&nitup->t_tid, BufferGetBlockNumber(buf), InvalidOffsetNumber);

	return nitup;
}

/*
 * Fills new root by rightest values from child.
 * Also called from ginxlog, should not use btree
 */
void
entryFillRoot(GinBtree btree, Buffer root, Buffer lbuf, Buffer rbuf)
{
	Page		page;
	IndexTuple	itup;

	page = BufferGetPage(root);

	itup = ginPageGetLinkItup(lbuf);
	if (PageAddItem(page, (Item) itup, IndexTupleSize(itup), InvalidOffsetNumber, false, false) == InvalidOffsetNumber)
		elog(ERROR, "failed to add item to index root page");

	itup = ginPageGetLinkItup(rbuf);
	if (PageAddItem(page, (Item) itup, IndexTupleSize(itup), InvalidOffsetNumber, false, false) == InvalidOffsetNumber)
		elog(ERROR, "failed to add item to index root page");
}

void
prepareEntryScan(GinBtree btree, Relation index, Datum value, GinState *ginstate)
{
	memset(btree, 0, sizeof(GinBtreeData));

	btree->isMoveRight = entryIsMoveRight;
	btree->findChildPage = entryLocateEntry;
	btree->findItem = entryLocateLeafEntry;
	btree->findChildPtr = entryFindChildPtr;
	btree->getLeftMostPage = entryGetLeftMostPage;
	btree->isEnoughSpace = entryIsEnoughSpace;
	btree->placeToPage = entryPlaceToPage;
	btree->splitPage = entrySplitPage;
	btree->fillRoot = entryFillRoot;

	btree->index = index;
	btree->ginstate = ginstate;
	btree->entryValue = value;

	btree->isDelete = FALSE;
	btree->searchMode = FALSE;
	btree->fullScan = FALSE;
	btree->isBuild = FALSE;
}